Studies on the Structural Properties of Actin, Myosin, Actomyosin, and the Interaction with Adenosine Triphosphate

The muscle proteins actin, myosin, and actomyosin have been investigated. Their electrophoretic behavior was examined. The molecular weights by light scattering and dissymmetry coefficients were also determined for each protein. From the last two quantities, it has been possible to show that the random coil is the best structure to assign to most of the proteins involved. Values of the root mean square separations of such random coils have been found. The effect of adenosinetriphosphate on these properties has been determined, and a mechanism proposed to account for the changes observed. The mechanism postulates the existence of an actomyosin complex of high molecular weight. This complex molecule dissociates in the presence of ATP, not into actin and myosin, but into complex molecules of smaller size. The experimental evidence for this mechanism is presented.